1. Field of the Invention
The present invention relates to an intake manifold for air intake which feeds engine air.
2. Description of the Related Art
There has hitherto been known an intake manifold which is provided in order to feed air to each cylinder of an engine and fabricated from multiple component members, which are formed by techniques such as welding.
Such an intake manifold is provided with multiple ducts each of which communicates with each of the cylinders. And when the intake manifold is formed form multiple divided component members, it is general practice to provide mating surfaces of the component members along the axial direction of the ducts.
A representative example of this construction is described in the Japanese Patent Laid-Open No. 7-148769, for example.
In an intake manifold described in the Japanese Patent Laid-Open No. 7-148769, ducts and space portions provided on the inlet side of the ducts are divided at mating surfaces provided along the axial direction of the ducts, and these are joined together at these mating surfaces to form an internal molded resin part. This intake manifold is constructed in such a manner that the inlets of the ducts themselves are divided at the mating surfaces.
In a case where a funnel portion is provided at the inlets of the ducts in order to make the flow of the air smooth, as in the intake manifold described in the Japanese Patent Laid-Open No. 7-148769, if the mating surfaces are provided in such a manner that the inlets of the ducts themselves are divided, the funnel portion itself is also divided.
However, it became apparent that when the intake manifold is constructed by positioning the mating surfaces in the funnel portion, even when the component members are brought into close contact with each other on the mating surfaces, the air flow becomes turbulent in these parts.
Therefore, the present invention provides an intake manifold which can smoothly introduce air into ducts without making the air flow turbulent when a funnel portion is provided at the inlets of the ducts.